Cs_(2)HfCl_(6)和Cs_(2)HfCl_(6)∶Tl晶体的生长、光学和闪烁性能研究

Optical and Scintillation Properties of Cs_(2)HfCl_(6) and Cs_(2)HfCl_(6)∶TlSingle Crystals Grown by the Bridgman Method

本文使用坩埚下降法制备了∅7 mm的未掺杂Cs_(2)HfCl_(6)与Cs_(2)HfCl_(6)∶0.2%Tl(摩尔分数)单晶,对晶体样品进行了物相、杂质含量、光学和闪烁性能的研究。该晶体属于立方晶系,空间群为Fm3m。在荧光和X射线激发下,未掺杂Cs_(2)HfCl_(6)晶体的发光主峰皆为380 nm,对应于自陷激子发光。Cs_(2)HfCl_(6)∶0.2%Tl晶体在荧光和X射线激发下,发射光谱中除了存在380 nm处的自陷激子发光,也存在505 nm处Tl^(+)的sp-s^(2)跃迁发光。Cs_(2)HfCl_(6)和Cs_(2)HfCl_(6)∶0.2%Tl晶体的光输出分别为37000 photons/MeV和36500 photons/MeV,在662 keV处的能量分辨率皆为3.5%。在137 Cs源激发下,Cs_(2)HfCl_(6)晶体的闪烁衰减时间为0.37μs(4.2%)、4.27μs(78.9%)和12.52μs(16.9%),Cs_(2)HfCl_(6)∶0.2%Tl晶体的闪烁衰减时间为0.33μs(3.5%)、4.09μs(81.9%)和10.42μs(14.5%)。

The∅7 mm undoped Cs_(2)HfCl_(6) and Cs_(2)HfCl_(6)∶0.2%Tl(mole fraction)single crystals were grown by the Vertical Bridgman method.The phase,impurities concentrations,luminescence and scintillation properties of crystal samples were studied.Both crystals belong to the cubic crystal structure and the space group of Fm3m.When excited by ultraviolet light and X-ray,both crystals exhibit an emission peak at 380 nm originated from self-trapped excitons emission,and Cs_(2)HfCl_(6)∶0.2%Tl crystal exhibits an extra Tl^(+)sp-s^(2) transition induced emission at 505 nm.Cs_(2)HfCl_(6) and Cs_(2)HfCl_(6)∶0.2%Tl possess high light yields of 37000 photons/MeV and 36500 photons/MeV respectively and both have excellent energy resolutions of 3.5%at 662 keV under excitation of 137 Cs source.The scintillation decay time of undoped Cs_(2)HfCl_(6) is comprised of 0.37μs(4.2%),4.27μs(78.9%)and 12.52μs(16.9%).The scintillation decay time of Cs^(2)HfCl_(6)∶0.2%Tl is comprised of 0.33μs(3.5%),4.09μs(81.9%)and 10.42μs(14.5%).